Fibre optic communications

Abstract

An encoder and an encoding method are suitable for use in an optical communication system. A concatenated coding scheme is used, in which the source data are encoded by means of an outer encoder to produce outer encoded data, and the outer encoded data are encoded by means of an inner encoder to produce inner encoded data, which are transmitted over a communications medium, such as an optical fibre. The inner encoder acts to produce inner encoded data in a format which occupies the space occupied one or more (for example, two) frames as defined in a standard, in this case the ITU-T G.709 standard. The inner encoder forms a product code from two sets of codewords, for example Extended Hamming codes. More particularly, at least one of the two sets of codewords is a shortened code, in order that the inner encoded data exactly occupies a plurality of frames as defined in the standard.

1 - 38 . (canceled)  
   
   
       39 . A method of encoding data, comprising: 
 encoding source data by means of an outer encoder to produce outer encoded data,    encoding the outer encoded data by forming a product code of Extended Hamming codewords to produce inner encoded data in a format which occupies 32640 bytes, and    transmitting the inner encoded data over a communications medium.    
   
   
       40 . An encoder, comprising: 
 an outer encoder, for encoding source data to produce outer encoded data,    an inner encoder, for encoding the outer encoded data by forming a product code of    Extended Hamming codewords to produce inner encoded data in a format which occupies 32640 bytes.    
   
   
       41 . A method of decoding data, comprising: 
 receiving encoded data over a communications medium in a format which occupies 32640 bytes, wherein the encoded data comprises a product code of Extended Hamming codewords;    decoding the received data by means of an inner decoder to produce inner decoded data; and    decoding the inner decoded data to produce outer decoded data.    
   
   
       42 . A decoder, comprising: 
 an inner decoder, for receiving encoded data over a communications medium in a format which occupies 32640 bytes, wherein the encoded data comprises a product code of Extended Hamming codewords, and for decoding the received data to produce inner decoded data; and    an outer decoder, for decoding the inner decoded data to produce outer decoded data.